merlin knows who all the bad guys are
the assassin gets to try and pick out merlin if the good guys win
percival (good) knows who merlin is (and so can try to be him to throw the assassin of)
mordred (bad) is not revealed to merlin
oberon (bad)does not reveal himself to the other bad guys or know who they are
morgana (bad) appears as merlin. if percival is in play he knows which two characters are merlin and morgana, but not which is which.

there's also a lady of the lake rule where the player that was leader (nominated the team) on the previous round gets to learn the identity of any player they choose. obviously they can say what they want but it's whether people believe them

there's also an optional rule where the leader not only nominates the team but also which quest they are doing. so, they all have to be done once only but will be done in another order.